The exemplary system relates to an improved system and method for treating biological tissue, and more specifically the skin layer, via an RF plasma gas-discharge at atmospheric pressures where the gas nozzle-electrode which serves as an RF-energy coupling antenna that functions in combination with an adjacent biological tissue acting as a second virtual electrode. Control of the gas discharge, or plasma, is effected in multiple ways including: gas nozzle-electrode configuration, nature of gas(es), and gas flow parameters. This system and method enables a broader range of skin treatment, resurfacing, and revitalization techniques to be applied that can be optimized to the needs of the treatment. Specifically, conditions for low temperature ablation of the skin layer minimizing thermal damage, controlled and localized heating of the skin layer, and transdermal ion delivery are achievable.
Skin treatment, such as skin resurfacing or revitalization, involves removal and/or modification of the outer and near-surface skin layer depending on the treatment needs. Skin treatments can be applied to needs such as wrinkle removal, pore tightening, skin smoothing, muscle lifting, collagen stimulation, lentigo (e.g. tattoo, scar, lesion, blemish, and hyper-pigmentation) removal, and hair removal and growth suppression. Previously proposed methods for skin treatment predominantly involve topical treatments which are either chemical in nature, such as creams or ointments, mechanical (i.e. abrasive), or a combination of both. These techniques have not demonstrated clinical efficacy in reducing skin treatment problems over a long-term period and preventing problem reappearance. In addition, chemical and mechanical “peeling” can have damaging effects on the problem skin area and/or surrounding tissue.
In addition, newer methods have been proposed for skin treatment utilizing laser, RF plasma, and LED light energy to interact with the skin layer. Each of the methods poses advantages and disadvantages to the application.
Previously available alternatives are characterized by disadvantages which are obviated by the exemplary system. Some of the problems associated with these types of techniques include: limited operating conditions, excessive skin heating and/or burning, incomplete blemish removal, extended healing periods, rashes, and other skin irritations and/or complications.
One example of a prior art system is disclosed in U.S. Pat. No. 6,105,581 assigned to ArthoCare Corporation. This patent teaches using an electrically-conductive solution, such as a salt solution, in contact with the skin and an electrosurgical probe. The application of RF-energy impulses to the probe produces a plasma in the solution causing cells on the surface of the skin and within the spine to be ablated. The solution removes heat from the plasma maintaining a low temperature which mitigates the problem of excessive skin heating associated with laser resurfacing. This technique has been referred to in the art sometimes as Coblation® technology. However, teachings of this patent have, as an inherent disadvantage, inadequate control of skin treatment region due to plasma “hot spots” being produced in various areas of the applied solution, and limited application due to the need for contact of the probe with the skin treatment region.
Another example of a prior art system is disclosed in U.S. Pat. No. 6,518,538 assigned to Mattioli Engineering Ltd. This patent teaches using an RF plasma gas-discharge to heat and selectively damage the skin layer. The skin layer to be treated is sealed to the probe and a vacuum is produced within the probe. An RF energy-coupled electrode and helium gas are introduced into the probe, whereby the plasma is produced. However, teachings of this patent have, as an inherent disadvantage, the limitation of operating under vacuum conditions, and the limitation of skin treatment regions suitable to probe position and obtaining suitable vacuum pressures without extraneous, adverse results.
Another example of a prior art system is disclosed in U.S. Pat. Nos. 6,629,974 and 6,723,091 assigned to Gyrus Medical Limited. This system uses an RF plasma gas-discharge of nitrogen to deliver its energy in a 6 mm spot to the treatment region. One of its major advantages over laser-based systems is that it does not depend on an intermediate chromophore to convert the RF energy into heat. Thus, heat dissipation is controlled and uniform. Furthermore, multiple passes of the plasma flame over the treatment area did not result in additive thermal damage as in laser-based systems. However, this system has, as an inherent disadvantage, the limitation of operating with only a small active plasma region for skin treatment. This is due, in part, to the fact that the plasma is ignited inside the housing of the device. This precludes any beneficial electromagnetic interactions between the electrode and the skin surface to assist in shaping the plasma profile.
Thus, there is a widely-recognized need for, and it would be highly advantageous to have, an improved system and method for heating biological tissue via an RF plasma gas-discharge devoid of the above limitation(s).